R-448A / Solstice N40 (commercial, zeotropic)
R-448A PT Chart
The full R-448A pressure-temperature reference table, from -30 to 130°F, with both the bubble and dew columns its 8 to 10°F glide requires. Use the dew point for superheat and the bubble point for subcooling. Cross-checked against the Honeywell Solstice N40 chart.
R-448A Pressure-Temperature Table
| Pressure (psig) | Bubble °F (subcooling) | Dew °F (superheat) |
|---|---|---|
| 10.4 | -30°F | -19.1°F |
| 17 | -20°F | -9.2°F |
| 24.9 | -10°F | 0.7°F |
| 34.2 | 0°F | 10.6°F |
| 45.1 | 10°F | 20.4°F |
| 57.8 | 20°F | 30.4°F |
| 72.3 | 30°F | 40.1°F |
| 89 | 40°F | 50°F |
| 108 | 50°F | 60°F |
| 129 | 60°F | 69.5°F |
| 154 | 70°F | 79.6°F |
| 181 | 80°F | 89.3°F |
| 211 | 90°F | 99.1°F |
| 244 | 100°F | 108.6°F |
| 281 | 110°F | 118.3°F |
| 321 | 120°F | 127.7°F |
| 365 | 130°F | 137.1°F |
Read the low-side (suction) pressure and its dew temperature for superheat, and the high-side (liquid) pressure and its bubble temperature for subcooling. The chart is in psig (gauge) and °F. To convert: kPa gauge = psig × 6.895; °C = (°F − 32) / 1.8.
R-448A PT Chart FAQs
What is the R-448A pressure at a 40F bubble point?
On the R-448A PT chart, a 40F bubble point corresponds to about 89 psig, where the dew point is 50F. At 211 psig the bubble point is 90F and the dew point is 99.1F. R-448A (Honeywell Solstice N40) is a zeotropic R-404A and R-22 replacement for commercial refrigeration, with a wide 8 to 10F glide.
Why does the R-448A PT chart have two temperature columns?
R-448A is a zeotropic blend, so at any given pressure it boils and condenses across a range of temperatures rather than at one point. The lower temperature is the bubble point and the higher one is the dew point; the gap is the glide, about 8 to 10 degrees F for R-448A, wider than most comfort-cooling refrigerants. The chart lists both columns so you read the correct one for each measurement.
Do I use bubble or dew point for R-448A superheat and subcooling?
Use the dew point for superheat and the bubble point for subcooling. Superheat is measured on the suction line where the refrigerant is fully vapor, which is the dew side. Subcooling is measured on the liquid line where it is fully liquid, which is the bubble side. Because R-448A glides 8 to 10 degrees F, using the wrong column introduces a large error, enough to misdiagnose a commercial rack charge.
What units is this R-448A PT chart in, and how do I convert to kPa or Celsius?
The table is in psig (gauge pressure) and degrees Fahrenheit, the field-standard units in North America. To convert pressure to kPa (gauge), multiply psig by 6.895. To convert temperature to Celsius, use C = (F - 32) / 1.8.
Related HVAC Tools
Superheat & Subcooling Calculator
Enter your R-448A readings; the calculator splits bubble and dew for you and returns the verdict.
R-449A PT Chart
The Opteon XP40 alternative commercial blend, with its own bubble and dew columns.
R-404A PT Chart
The refrigerant R-448A replaces, read on a single saturation column.
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